The present invention relates to a circuit breaker draw-withdraw apparatus for use with a circuit breaker to move the circuit breaker so as to be connected to or be disconnected from a plug-in base.
Conventionally, a plug-in base for a circuit breaker is mounted on a panel board or other base structure and is wired to circuitry on the base structure. A circuit breaker is installed in the plug-in base by inserting stabs protruding from the circuit breaker into jaws fixed to the plug-in base. The jaw/stab connection provides the primary electrical connection between the circuit breaker and the plug-in base. This connection may also mechanically retain the circuit breaker in the plug-in base.
Withdraw mechanisms have been developed for mechanically drawing a circuit breaker into a plug-in base and withdrawing the circuit breaker from the plug-in base. An example of such a withdraw mechanism is disclosed in U.S. Pat. No. 5,837,949 to Green et al. The withdraw mechanism described in Green et al. is operated by rotating a screw linkage using a drive tool inserted into the front of the withdraw mechanism which draws the circuit breaker into or withdraws the circuit breaker from the plug-in base. This type of mechanism is advantageous since a circuit breaker unit having a high amperage rating is heavy and thus is difficult for a technician to position properly in the plug-in base by hand. In addition, the jaws in a high amp plug-in base may require a high insertion force, making it difficult or impossible for a technician to apply sufficient force to fully insert the stabs into the jaws.
A circuit breaker withdraw mechanism typically includes a component attached to the plug-in base and a component attached to the circuit breaker. Installation of the withdraw mechanism may take place in the field, in a supplier warehouse or at the circuit breaker production plant. Accordingly, there is a need to ensure that attachment of the withdraw mechanism be simple and fool-proof.